The appropriateness of treatment of supraglottic carcinoma with post-operative radiotherapy is still a controversial issue. The purpose of the present work has been to define the effectiveness of post-operative radiotherapy in the treatment of supraglottic carcinomas and to discuss, on the basis of the data reported in the literature, the usefulness of combined surgery-radiotherapy. The study involved 97 subjects suffering from spinocellular carcinoma of the laryngeal vestibule (95 males, 2 females; average age: 58; age range: 38-89 years) who underwent horizontal supraglottic laryngectomy together with bilateral laterocervical lymph node dissection. Of these patients 35 (36%, group A) had undergone a cycle of prophylactic radiotherapy (60-70 Gy in fractions of 2 Gy/die, administered with two side fields), after surgery. The remaining 62 cases (64%, group B) did not have any additional therapy after surgery. For both groups the overall actuarial survival and 5-year corrected survival rates were calculated; statistical significance was calculated using the Wicoxon test. For group A the overall actuarial survival and corrected actuarial survival rates were, respectively, 74% and 90%. For group B these rates were, respectively 61% and 80%. A statistical comparison of both parameters did not show any statistically significant difference (p = 0.2 and 0.4, respectively). In reference to tumor extension, established both on the basis of clinical (T) and surgical-anatompatholgical (pT) findings, no significant differences were encountered between the overall actuarial survival and corrected actuarial survival rates for the two groups of patients (p > 0.05). In NO patients significantly higher overall actuarial survival rate in those patients who underwent the combined surgery-radiotherapy treatment than in those treated with surgery alone (p = 0.01) was seen. This was not, however, confirmed by the corrected actuarial survival rates and comparative analysis of the groups for surgical staging of the lymph node metastases (p > 0.05). Most likely the different behavior seen in the two groups depends on possible errors in the clinical staging of N due to the presence of reactive lymphadenitis and micrometastases. In conclusion, the data derived from the present research indicate that post-operative radiotherapy, performed as prophylaxis in cases undergoing supraglottic laryngectomy does not yield any statistically significant improvement in prognosis. Therefore, the radiotherapy association should be ruled out in those patients where the oncological radicality of the surgery is reasonably certain. It can possibly be considered as integration to surgery, only in those cases where radicality is in doubt.